I was recently in a dialog with some other writers where the issue of the portrayals of race and gender came up with regards to writing. The question came up of whether it's taboo to portray anyone who is not a white male in a negative light. This is a tough thing to discuss, because it has the potential to go off in so many different directions. First of all, of course, I think it's very possible to make a case that no such taboo exists, and that there are in fact plenty of examples in contemporary fiction where villains, minor characters and flawed protagonists exist who are not white males. The "taboo" in question is more about portraying people who have been underrepresented in a particular genre of fiction (or the media in general) in a stereotypically negative light.
A female character who is overly emotional, vain, bad at math, and who lacks a sense of the big picture may raise some hackles, especially in the absence of female characters in said story with different qualities. This does not mean that there aren't some women out there who really have some, or even most, of the negative traits traditionally associated with femininity (one can also argue that the assessment of some traits as negatives is subjective as well, but that's another topic). But women have been historically been denied access to many rights and choices based on these stereotypes. Some of us are even old enough to remember being told that certain careers were inadvisable or that certain activities or behaviors were just not appropriate for us.
So guess what? The stereotypes still rankle sometimes.
I think one can make the same argument for negative stereotypes associated with cultures, ethnicities, religions and orientations that have historically been in the minority, or historically had their humanity denied based on these stereotypes. There may be a time when these stereotypes are so comfortably in history's rear window--far enough away from the daily lives and experiences of the people who have been their victims for them to not be so hurtful--but I really don't think that we're there yet.
I think, also, that there is another issue that people often forget. There is no way to write any character in a way that will please or appeal to everyone or represent the "true and quintessential" experience of being a member of a particular group or subgroup of humanity. Lest one throws up ones hands and says, "Well I'm damned no matter how I write a minority or female character, so I'll just avoid writing them entirely," I'll point out that the relatively limited number of women and minority characters in traditional fantasy is precisely why one ends up feeling like every character from such a group is an ambassador for his or her entire group--something no one person or character can ever be. The only solution is to write a variety of characters and to do so with a reasonable amount of care and awareness of negative stereotypes while still allowing your character to be an individual.
Issues related to identity are still confusing at times. Most of us belong to many groups simultaneously, and we may identify more strongly with some than others. If you belong to a group that has been treated by our culture as the default "norm," you likely don't spend as much time thinking about it as you do thinking about your identities that lie outside that perceived "neutral" status (which, I hate to say, in the US, is still white, male, Christian, heterosexual etc).
I think one promising development is that we live in a time and place where very few people self identify, let alone take pride in, being prejudiced. This means that it is natural to feel a mixture of shame, fear, and guilt when someone suggests that one has expressed a prejudice of some kind. It's easy to get angry or defensive or deny the accusation categorically. Sometimes the hardest thing of all is to listen to someone else's arguments and to spend some time thinking about whether there is any truth in them or whether they are simply one person's opinion.